I'm afraid you can't be forgiven for this. It can't be done. Not by me, anyway. But I will say that from the additional information you provide above, about how three of these coins were marked in a similar way, that it sounds like a crude banker's mark, also called a countermark.
These markings were made in Owls and other ancient coins primarily for two purposes, to test the integrity of the metal underneath (make sure it was solid all the way through, not plated), and to certify the coin as legal tender in a location other than where it was minted (with very early coins, such as the Lydian trite to the left that I'm using as my avatar here, countermarks are thought to be designations of ownership, with some of these coins today having more than a dozen such marks). Typically, very little metal was lost through this process. The metal, rather than being chipped off, was merely pushed to the sides of the mark. Countermarked coins, like test-cut coins, typically have the same weight as coins not marked in this way.
Coins with banker's marks can be quite collectable -- some of the marks themselves can be attractive -- but they typically sell for less than coins not marked. Some people specialized in collecting them.